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(No Model) l C. A. RANDALL.

. l TTLEPHUNIC TRANSMITTER.

No. 295,806. TatenteaT/m. 25. 1884.

N. Pneus nmuuwmpalr. www.. n. c.

'i lNiTED STATES "PATENT OYEEIGE,

.cEAELEs A. RANDALL, oE NEW vonk, N. Y.

TELEPHONIC TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 295,806, dated March25, 1884.

Application led May 3, 1883. (No model.)`

.To all whom, it may concern."

Be it known that I, CHARLES A. RANDALL, a citizen of the United States,residing at New York, in the county and State of New York, have inventednew and useful Improvements in Telephonie Transmitters, of which thefollowing is a specification.

This invention relates to that class of telephonictransmitters in Whichthe movements of a vibrator under the inliueuce` of soundwaves arecommunicated to the current-varying electrodes through anamplifying-lever. This type of -transmitter is illustrated inPatentsNos.` 235,019, 235, 020,238,434, and 255, 333, heretofore grantedto me, and is designed to secure a greater range of variation ofcontactpressurc between the electrodes than is possible vbetweenelectrodes acted upon by thedirect movement of a diaphragm or vibrator.

The objects of my presentimprovem ent are, first, to obviate thenecessity for adjusting the electrodes under variations of temperatureor other conditions; second, to dispense `with spring-supports forelectrodes, such supports being liable to variations of tension, which`interfere with the proper action of the electrodes and render frequentadjustments necessary; third, to remedy the abrupt and irregularbreaking and varying of the electric current by the'jostling unsteadymovements of electrodes mounted on independent supports under theiniiuence of loud or abrupt sounds; fourth,to reduce thewear between thecurrentvarying electrodes; fifth, to obviate injury to the electrodes byelectric sparks; sixth, to prevent the` electrodes from beingdisarranged by expansion and contraction of the diaphragm or othervibrator, which gives motion to the amplifying-lever.

With these objects in view my invention consists in a new mode ofsupporting the electrodes in their proper relative positions, and incertain novel combinations of devices,which will be readily understoodfrom the following particular description, in connection with theaccompanying drawings, in which-- Figure I is a rearperspective view ofa transmitter constructed according to my invention. Fig. 2 is anenlarged longitudinal section of one ofthe long arms of theamplifying-lever and diametric section of the movable contactpiecescarried thereby. Fig. 3 is a side View of an instrument in which thevibrator is moved by the variations of attraction in the core of anelectro-ma net. Referring toFig. l, the letter D designates a diaphragmwhich may be supported in the usual manner, and provided with amouthpiece, which is not shown in this figure, from the fact that it isa rear view. v

The letter S indicates a metallic rock-shaft mounted in bearings s s,and having an upwardly-projecting short arm, L, which is connected withthe center of the diaphragm by a link-rod, R. Three long arms, L L'L L3,de- 65 pendfrom the shaft S, and two, `L2 and L3, are insulated from theshaft and the other long arm and the short arm. These long arms, theshort arm, and part of the shaft compose, es-

sentially, a mechanical lever having one short 7o and three long arms,and thevibrations of the diaphragm will be amplified by all the longarms, in accordance with the proportion v between their length and thelength of the short arm. Vhen it is desired to use only one of theseblock-supporting arms, arm L would preferably be selected, as itsextension or short arm is the means by which the vibrator controls thecontacts. Each of the long arms has mounted loosely upon it, in thepresent instan ce, two cylindrical blocks of carbon, C C, perforatedcentrally for the passage ofthe rod, and held in place upon said rod bya suitable shoulder or abutment, against which the bottom block rests.In one instance an adjustable nut, N, screwed upon the rodtis used. Inanother instance a pin, P, which may be passed through any one of aseries of holes in the rod; and in still another instance a rubberwasher, W, lwhich hugs the rod, but may slide thereon. In all threeinstances the blocks are adjustable, in order that they may be broughtto the most effective position on the rod. Of course, one block C oneach rod would vary the contact, and hence the circuit; 9 5

but I have shown two, as preferable in givin a greater degree ofvariation. The two blocks C G of each rod are connected by a iine wire,f, i and one of the blocks-no matter whichuponeach rod, is connected to`a leading-oftwire, these wires being respectively desig= nated by thelettersY, Y', and Y2. The arms L', L2, and Ii3 are respectivelyconnected to binding-posts B, B', and B2 by Wires y, g/ ,and y?,

and these binding-posts are connected to separate batteries G G G2,having' opposite con` nection to ground or otherwise. rIhe wires Y, Y',and Y2 are connected to binding-posts 133,]3, and B5, and are eachsupposed tohave nal 1o ground-connections, but may be intermediatelyconnected in line-circuits including receivinginstruments, or to primarycircuits of induction-coils, the secondary coils of which are connectedin main lines. The said Wires may be connected to independentline-circuits, or

they may all be connected to the same main line, or all to oneinduction-coil primary. When they are connected to one circuit, the

currents of all the batteries will of course be 2o combined upon suchcircuit. Imore especially contemplate their union with one line, so thatall the currents of all the batteries, as varied by all the contacts,shall be jointly in one circuit, obtaining thus a larger quantity ofcurrent with the electro-motive force of one of the sections of battery.In addition, while the danger of non-adj ustment or lack of properrelation between the electrodes for effective work is reduced to aminimum, if such danger should become a reality in one set ofelectrodes, the' instrument Wound remain operative, because of theremaining sets.

The perforations of the blocks C C are of a size, as clearly shown inFig. 2, to permit some considerable play of the contact-blocks upontheir supporting-arms, the vibration of an arm causing a correspondingplay or sliding of its contact-blocks within their range of motion.

'Ihe operation is as follows: rIhe arms are Aro given normally such aninclination `that the interior walls of the perforations through theblocks will rest upon and contact with the supporting-arms. Vhenthediaphragmisvibrated by the impingement of sound-waves upon it,

its movement is transferred to the short arm of the lever system, thenceto the long arm, at whose extremity it is largely amplified. Themovement or vibration there is sufficient to jostle or move the blocks,or to cause them to 5o have a slight play around the supporting-rodsufficient to vary the contact between them, and so vary and control thecurrent in the circuit. The amount and rapidity of these variations willof course depend upon the rapidity and amplitude of the vibrations or.

. except that the vibrator D is the armature of an electro-magnet, asshown at M. This magnet may be connected in one main line, and

the instrument serve as a repeater to transmit the message over one ormore other lines connected with it, as already described, or may be usedas a relay.

In my transmitter as now described, it will be seen that there are nonice adjustments requiring attention. In fact,` after the contactblocksare first given a proper position on their supporting-arm the instrumentnever requires any further adj ustment; also, there are noelectrode-supporting springs, which would by their changes of tensionrender frequent adjustment necessary. It will also be noted that thecontact-blocks are in such position to each other and theirsupporting-arm that they cannot easily be irregularly thrown or vibratedout of operative position by abrupt, loud, or violent sounds at thetransmitter. Another advantage is that as the electrodes havecomparatively large contact-surfaces the wear in use is much less thanwhen two small points only are in contact, as is the usual method. Itshould also be noticed that, owing to the large contact-surfaces of theelectrodes, larger batteries can be used than heretofore without injuryto the electrodes by sparks at the breaking yof contact. Finally, itwill be observed that as one electrode is carried by the other therewill be no disarrangement of their proper relative positions by eX-pansion and contraction of the diaphragm or motive vibrator. y

Having now described my invention and eX- plained the operation thereof,I wish it to be understood that I do not confine myself to any of theparticular constructions or arrangements shown in my drawings, but mayvary any or all of them in any manner for the elflcient carrying out ofmy invention without departing from the essential principles thereof.

Vhat I claim isl. In a telephonie transmitter, the combination of anamplifying vibratory lever forming one electrode, and the oppositeelectrode mounted loosely thereon and supported thereby, so that thecontact of the two electrodes may be varied, substantially as described.

2. In a telephonie transmitter, the combination of a diaphragm orvibrator, an amplifying-lever operated thereby and forming an electrode,and an opposite or second electrode loosely mounted upon the long arm ofthe lever, the two electrodes being arranged and adapted to -varycontact Vupon movement or vibration ofthe lever, substantially asdescribed.

3. rIhe combination of a lever forming one electrode, a secondfelectrodeloosely mounted thereon and carried thereby, and means, substantially asdescribed, for adjusting or regulating the position ofthe secondelectrode upon the first, as set forth.

4. The combination,with the diaphragm and short lever-arm connectedtherewith, of a plurality of long lever-arms provided with electriccontact-surfaces and connections, substan- IIO i by, each lever -formingone electrode loosely carrying and supporting a second electrode, aseries of batteries-one for each lever and connected thereto--andconnections to the line or lines from the second electrodes,substantially as described.

In testimony whereof Ihave hereunto set my hand in the presence of twosubscribing Witnesses. y

C. A. RANDALL.`

Vitnesses:

J. W. HUGHES,

W. J, CAHooNE.

